The Real Housewives of New York City

Lesson to all would-be cheaters: If you're going to be unfaithful, don't let Patti Stanger see it.

On Thursday's Watch What Happens Live, the Millionaire Matchmaker star told a shocked Andy Cohen that she was a firsthand witness to Mario Singer stepping out on his now-estranged wife Ramona Singer.

Now, Stanger has exclusively talked to PEOPLE to fill in the details of the night when she "saw the whole thing go down." In fact, Stanger says she witnessed what she believes was the beginning of Mario's long-term affair with twenty-something Kyle "Kasey" Dexter.

Her divorce from Jason Hoppy may not be finalized yet, but Bethenny Frankel is 100 percent positive that she never wants to walk down the aisle again.

In an interview on Bravo's Watch What Happens Live, host Andy Cohen asked the Real Housewives of New York star if she still believed in marriage following the nasty, public split from her estranged husband.

"I will never get legally married again," she told Cohen. "It doesn't mean that I would not commit to someone, and I'm not jaded or bitter about love. I think there are amazing guys out there, but I will never, ever be legally married again."